Half the participants applied sunscreen every day and the other half continued to apply sunscreen as they would normally.

After 15 years, the number of people who developed melanomas from the discretionary sunscreen group was twice that of the group who had applied daily sunscreen in the trial.

"These findings now provide some assurance to medical professionals, public health authorities and the general public, that the regular application of sunscreen is likely to be beneficial with regard to melanoma protection," said lead researcher Adele Green.

"And while sunscreen use is an important part of Skin cancer prevention, they of course are not the whole solution: other sun protection measures should be continued too," she added.